This application is related to and claims priority from Japanese Patent Applications No. Hei. 10-329750 filed on Nov. 19, 1998, No. Hei. 10-329857 filed on Nov. 19, 1998, and No. Hei. 10-330718 filed on Nov. 20, 1998, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a cooling device for cooling a heat-generating member by boiling and condensing refrigerant.
2. Description of Related Art
A conventional cooling device has a refrigerant tank where refrigerant is boiled by heat from a heat-generating member, and a radiator where gas refrigerant from the refrigerant tank is condensed. In the cooling device, for cooling a heat-generating member such as a computer chip disposed in a printed bade plate, it is necessary for the heat-generating member to be attached onto an attachment surface of the refrigerant tank. In this case, a core portion of the radiator is disposed to be not protrude from the attachment surface of the refrigerant tank. Therefore, one side ends of the first and second headers of the radiator are inserted into the refrigerant tank from a surface opposite to the attachment surface to be not protrude from the attachment surface. However, in the cooling device, liquid refrigerant introduced into the first header together with gas refrigerant from the refrigerant tank may flows into radiator tubes from the first header, and radiating performance in the radiator is decreased. Further, when the radiator tubes are arranged in upper and lower two lines, liquid refrigerant condensed in the first header falls along an inner surface of the first header and may be introduced into the radiator tubes from opened ends of the radiator tubes opened in the first header. Therefore, refrigerant does not effectively circulate between the refrigerant tank and the radiator.
On the other hand, in the cooling device, when a duct enclosing the first and second headers of the radiator is disposed so that outside fluid is effectively blown toward a core portion of the radiator, the first and second headers may restrict the flow of the outside fluid, and the outside fluid may be not effectively blown toward the core portion of the radiator. Further, in this case, an unnecessary clearance may be formed between the first and second headers and the duct.
In view of the foregoing problems, it is an object of the present invention to provide a cooling device having a refrigerant tank and a radiator, which restricts liquid refrigerant from being introduced into tubes of the radiator.
It is an another object of the present invention, to provide a cooling device having a refrigerant tank and a radiator, in which outside fluid is effectively introduced into a core portion of the radiator.
According to the present invention, a cooling device includes a refrigerant tank having a boiling space between first and second wall surfaces, in which a part of liquid refrigerant is boiled and vaporized into gas refrigerant by absorbing heat from the heat-generating member attached onto the first wall surface, and a radiator for condensing refrigerant from the refrigerant tank. The radiator has a first header into which gas refrigerant from the boiling space of the refrigerant tank flows, a plurality of tubes in which gas refrigerant from the first header is cooled and condensed by performing heat exchange with outside fluid passing through the radiator, and a second header through which liquid refrigerant condensed in the tubes returns to the refrigerant tank. The second wall surface of the refrigerant tank has a first connection portion communicating with the boiling space at a gas refrigerant outlet of the refrigerant tank, and a second connection portion through which the second header communicates with the boiling space. In the cooling device, the first header is connected to the first connection portion to be approximately perpendicular to the second wall surface, the second header is connected to the second connection portion to be approximately perpendicular to the second wall surface, and the gas refrigerant outlet has a lower end disposed at a position lower than a lower end of the tubes opened into the first header. Thus, even when condensed liquid refrigerant stays in the first header, liquid refrigerant is prevented from flowing into the tubes, because liquid refrigerant flows into the boiling space through the gas refrigerant outlet when the a liquid refrigerant surface within the first header becomes higher than the lower end of the gas refrigerant outlet.
Preferably, the first header has an inserted end portion being inserted into the refrigerant tank from the first connection portion, the inserted end portion has a communication port through which the first header communicates with the boiling space, and the communication port has a lower end disposed at a position lower than the lower end of the tubes opened into the first header. Therefore, when a liquid refrigerant surface within the first header becomes higher than the lower end of the communication port, liquid refrigerant flows into the boiling space through the communication port and the gas refrigerant outlet. Thus, liquid refrigerant is prevented from flowing into the tubes.
Preferably, the tubes are arranged in upper and lower two lines between the first and second headers, and the first header has therein a partition wall for partitioning the tubes on the upper line and the tubes on the lower line within the first header. Therefore, even when condensed liquid refrigerant falls from an inner wall surface of the first header, the partition wall prevents the condensed liquid refrigerant from directly introduced into tubes on the lower line.
Further, the tubes have inserted end portions being inserted into the first header to protrude inside from an inner surface of the first header. Therefore, even when liquid refrigerant flows into the first header from the boiling space with the flow of gas refrigerant, gas refrigerant and liquid refrigerant can be separated by the inserted end portions of the tubes within the first header. Thus, gas refrigerant is introduced into the tubes, while liquid refrigerant is restricted from flowing into the tubes.
Preferably, the first header has a side wall surface contacting outside fluid in a flow direction of outside fluid, and the side wall surface is provided in such a manner that outside fluid contacting the side wall surface flows toward a core portion of the radiator. Therefore, outside fluid can be effectively introduced toward the core portion, and radiating performance of the radiator can be improved.